Toronto (Canada), Aug 12 : Tommy Paul ended Carlos Alcaraz's 14-match winning streak when he upset the World No. 1 in quarter-finals at the Canadian Open, here. The American struck the ball cleanly to down the top seed 6-3, 4-6, 6-3 and reach his maiden ATP Masters 1000 semi-final on Friday night. The 26-year-old, who defeated Alcaraz last year in Montreal, displayed all-court coverage and often looked for opportunities to move forward to earn his first win over a World No. 1. "I played a really good match today. I really went after my shots. You can't start any points on your heels against him or he'll take advantage of that. So you really have to go after your shots early in the rally and I was feeling really good on the first-strike tennis. That was the difference today," Paul said in his on-court interview. The 12th seed won 21 of 23 net points and rushed Alcaraz with aggressive returns throughout the two-hour, 20-minute battle, in which the Spaniard committed 17 unforced forehand errors. Despite being broken while serving for the opening set at 5-2, Paul stayed focussed to close the set in the ensuing game. Alcaraz grew frustrated with his unforced errors, while the World No. 14 showed smooth transition from defence to offence to reach the last four. The Spaniard increased his level as he won 10 consecutive points from 2-3 in the second set, during which he struck a tweener past Paul that brought the Toronto crowd to their feet. But it was Paul who gained an advantage by earning a break in the sixth game of the final set and won 76 per cent of points behind his first serve in the decider. The one-time tour-level titlist improved to 2-1 in his Lexus ATP Head to Head series with Alcaraz, who slipped to 49-5 on the season. Last year, Paul saved a match point to down Alcaraz in Montreal. A semi-finalist at this year's Australian Open, Paul will next meet seventh seed Jannik Sinner. The New Jersey native is at a career-high No. 12 in the ATP Live Rankings. On the other hand, Alcaraz, who has collected a season-leading six tour-level titles, suffered his first loss since Roland Garros. It was also his first quarter-final loss of 10 appearances in the last eight this year. He could meet Paul again next week in Cincinnati, where they are seeded to meet in the third round. /IANS